I just bought a mayflower apc and a haley D3 chest rig and I have been looking for armor to go in it. I have managed to acquire a set of ceradyne ballistic upgrade plates but i need to get plate backers for them as they are not stand alone plates. So my main questions I know that they are IV plates anyone ever seen these plates?

Also other than X-ray is there a good way to check them? These plates are old but look to never have been worn. the only way I have seen plates being check was putting them on the edge of the table and pressing on them to hear for any noise. That is how they checked my plated before I deployed and it just seemed wrong to me.

Would it be better to buy a set of used esapi plates or a new set of cheaper ceramic plates or even some ar500 plates vs buying the soft armor backers?

And this might be a dumb question but do plates go bad? These have a manufacture date of 0401 not sure if that is 2004 or 2001 but either way they are old